Folks - Is there any way one can alter the mixture of a gdi Plus4 -- mine is definitely running rich as the exhaust is a very solid black colour. the car says I am getting circa 32mpg which is surely awful!! even more so as the budget here has just put a carbon tax on fuel!!!
No there is no way a punter can alter the mixture on a modern car.
The ECU gets all its inputs from various sensors and alters the mixture mixture as advised by the map that is in the ecu as it also adjusts the ignition timing again with reference to the map.
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